1. Field of the Invention
The present invention relates to encoding apparatuses and methods and decoding apparatuses and methods, and, in particular, to an encoding apparatus and method, and decoding apparatus and method for realizing an increase in speed of video stream decoding.
2. Description of the Related Art
It has been proposed (see, for example, Japanese Unexamined Patent Application Publication No. 11-341437) that, in order to quickly start video stream decoding, when a video stream is encoded, a frame-recording position designated by a user is recorded as index data, and, when the video stream is decoded, the index data is used to detect a position to start the video stream decoding.
In addition, in order to increase the speed of video stream decoding, it is possible to perform dividing the decoding into a plurality of threads, and using a plurality of processors to execute the threads in parallel. For example, for a video stream encoded in the MPEG-2 (Moving Picture Experts Group-2) standard (hereinafter referred to as “MPEG-2”), decoding of the video stream is divided, with each slice in a picture used as a unit. Specifically, in a case in which decoding is performed in divided form by four processors, as shown in the left part of FIG. 1, when a picture includes sixteen slices, the processors perform parallel decoding of the slices one by one in order from the top slice in the picture. In other words, the processors decode any one of four sets of slices 1-1 to 1-4, slices 2-1 to 2-4, slices 3-1 to 3-4, and slices 4-1 to 4-4 shown in the right part of FIG. 1.